McNealy's testimony contrasted with that of Jonathan Schwartz, who became Sun's CEO after McNealy and was also on the stand Thursday. Schwartz emphasized Java's openness and testified that Sun never felt it had grounds to bring a lawsuit against Google.

The two were testifying in the second week of Oracle's lawsuit against Google, in which it accuses the company of infringing Oracle's Java patents and copyrights in the Android OS. Oracle acquired the rights to Java when it bought Sun in early 2010.

McNealy co-founded Sun in 1982 and was its chairman and CEO until 2006, when he handed the CEO title to Schwartz. He remained chairman until Oracle bought Sun.

The former Sun chiefs disagreed with each other on several issues, and the jurors will have to choose who to believe.

For example, Schwartz suggested his blog at Sun reflected the company's corporate policy and that his blog posts were "the equivalent of holding a press conference." A 2007 post from Schwartz congratulating Google on Android's release has become an important piece of evidence at trial.

However, McNealy said twice he had never read Schwartz's blog, and that Sun's policy on blogs was that they were "not corporate but rather personal things."

They also disagreed on whether companies needed a license to use Sun's application programming interfaces for Java, a central issue in the case. McNealy said Sun licensed its APIs and compared them to "architectural drawings" -- similar to Oracle's characterization of the APIs as "blueprints."

Schwartz testified that companies could use Java without a license so long as they didn't claim to be "Java compatible" and use the Java logo.

Attorneys for each side tried to undermine the jury's confidence in both men's testimony. Robert Van Nest, an attorney for Google, suggested to McNealy that he was a "close personal friend" of Oracle CEO Larry Ellison and that he had made "a great deal of money" when Oracle bought Sun.